The Würm is a river in Bavaria, Germany, right tributary of the Amper. The length of the river is 39.8 kilometres (24.7 mi), or 76.3 kilometres (47.4 mi) including the Steinbach, the main feed of Lake Starnberg. It drains the overflow from Lake Starnberg and flows swiftly through the villages of Gauting, Krailling, Planegg, Gräfelfing and Lochham as well as part of Munich (in the borough of Pasing) before joining, near Dachau, the Amper, which soon afterwards flows into the Isar and eventually flowing into the Danube.